1. Field of the Invention
The present invention pertains to row crop harvesters and more particularly relates to root crop harvesters of the type employing multiple picking heads for simultaneously harvesting two planted rows.
2. Description of Prior Art
Single row root crop harvesters which include a plow for loosening the crop from the soil, a picking head including a pair of endless lifting conveyors for gripping the foliage and lifting the crop from the soil and thereafter delivering the crop to a severing mechanism, are well known in the art as evidenced by U.S. Urschel Pat. No. 2,562,400 which issued on July 31, 1951. The Urschel harvester is coupled to the draw bar of a tractor for movement through the field. In order to align the picking head with the single row being harvested, the entire harvester is moved laterally of the tractor by an operator seated on the harvester in position to manually move a lever which pivots a coupling device connecting the tractor to the harvester. The lever may also be pivoted in a vertical plane to raise or lower the resiliently supported front end of the picking head.
An earlier version of the Urschel single row harvester is disclosed in Urschel U.S. Pat. No. 1,894,802 which issued on Jan. 17, 1933. This patent discloses a self propelled beet harvester provided with a plow, a picking head, and two roller bar units for receiving the foliage of beets being harvested. The single picking head is mounted near its upper end for pivotal movement about horizontal and vertical axes. A hand lever and suitable linkage are provided for adjusting the height of the forward end of the picking head through a resilient connection which allows the forward end to follow the ground contour during harvesting. Foot pedals are provided for moving the forward end of the picking head transversely during harvesting. This patent, however, does not disclose a harvester having two picking heads with one head being transversely locked to the vehicle in a predetermined position so that simply steering the vehicle aligns that head with one of the rows being harvested, while the operator is free to independently shift the other head transversely relative to the first head to follow the other row being harvested.
Urschel U.S. Pat. No. 1,964,896 which issued on July 3, 1934 discloses a row crop harvester that is similar to Urschel U.S. Pat. No. 1,894,802 but is provided with roller bar units that are mounted on the upper end of the picking head for movement therewith.
Spiegl U.S. Pat. No. 2,368,895 which issued on Feb. 6, 1945 discloses a two row crop harvester having the upper ends of two picking heads pivotally mounted for movement about horizontal and vertical axes. The vertical position of the forward end of each picking head is maintained above the ground by a lever and suitable linkages. The transverse position of the forward end of the two picking heads are simultaneously adjusted by a crank and threaded rod that moves a V-shaped spreader longitudinally to spread or retract tongs connected to forward ends of the two heads. Although the above transverse adjustment may take place during harvesting, it will be recognized that it is much more inaccurate and difficult to coordinate the steering of the vehicle with the simultaneous lateral (and vertical) adjustment of both picking heads as required by Spiegl, than it is to center one head with one row by steering the vehicle and independently adjusting the other head transversely to follow another row as in the present invention.
U.S. reissue Pat. Re No. 20,151 which issued to Urschel on Oct. 27, 1936, discloses several forms of severing mechanisms of the roller topping bar type used in conjunction with harvesting row crops including cotton and corn as well as root crops.
U.S. Pat. No. 3,201,928 which issued to Claas on Aug. 24, 1965 discloses a multiple row corn harvester wherein the guide members for introducing stalks of corn to the picking heads may be laterally pre-adjusted for a particular row spacing, which spacing is stated to vary according to soil and weather conditions. Although the guide members are adjustable to the row spacing of the plants, no provision is present in the Claas apparatus which would permit adjustment during operation.